The contrasting richness of this dish of baked fish, potatoes and roasted chili-garlic salsa served with fresh and crunchy jicama salad is typical of Mexico's bold and flavorful dishes--it's great because it's so simple. You can use a variety of firm white fish fillets--whatever's available--and if you're really pressed for time, you could buy a good quality salsa from the refrigerated or deli section of the supermarket and mix it with plenty of chopped fresh cilantro.